Metallic salts of higher molecular weight fatty acids are commercially known as metallic soaps. Metallic soaps are well known and have been widely used in the industries of resins, paints, papers, fibers, greases, etc. as stabilizers, lubricants, water-repellents, thickeners, coating agents, for example. In addition to such uses, metallic soaps are used as catalysts in chemical reactions, and also as additives for rubber to improve adhesive properties or bonding of the rubber with steel cords.
The methods known in the art for industrial production of metallic soap include various methods. One of them is the double decomposition (aqueous) method wherein a water-soluble metal salt and a metal salt of a fatty acid are reacted in an aqueous solution state to produce water-insoluble metallic soap. Another method of producing metallic soap is the fusion process, in which a form of a metal is employed, including metal alkoxides, metal oxides, metal hydroxides or metal carbonates and the like, and a fatty acid are reacted by fusing these at a temperature above the melting point of the metallic soap to be formed, and by-produced water and/or carbon dioxide gas is expelled out of the reaction system, whereby the metallic soap is taken out in a molten state. Another method for the production of soaps is through phase transfer catalysis. Phase transfer catalysis is a synthesis method which allows the use of relatively simple two-phase reaction systems in the place of solvent systems which may be toxic and/or expensive. In fundamental terms, phase transfer catalysis employs a phase transfer catalyst which facilitates the transfer of a reactive species from the first phase, normally aqueous, into the second phase, normally organic, where the desired reaction can take place. Various processes for making metallic soaps have been described in the art, including U.S. Pat. No. 4,397,760, U.S. Pat. No. 4,927,548, U.S. Pat. No. 4,235,794, U.S. Pat. No. 4,307,027, U.S. Pat. No. 5,274,144, and U.S. Pat. No. 2,650,932, the disclosures of which are herein incorporated by reference in their entireties.
In particular, the fatty acids referenced above can be obtained by any suitable source of natural fats, including natural oils. Further, the metals referenced above may include non-limiting examples such as beryllium, magnesium, manganese, calcium, lithium, sodium, strontium and barium; transition metals such as titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, molybdenum, palladium, silver, cadmium, tungsten and mercury; and other metals such as aluminum, gallium, tin, iron, lead, and lanthanoid metals. Metallic soaps have been synthesized from natural oils by saponifying the oils with varying quantities of a metal compound such as metal oxides, metal carbonates, metal hydroxides, or metal alkoxides. Generally, saponification means either the neutralization of fatty acids to produce soap or the saponification of fats and/or oils to produce soap. Saponification involves hydrolysis of esters under basic conditions to form an alcohol and the salt of a carboxylic acid (carboxylates). More specifically, the use of fatty acids and the addition of specific types and amounts of natural oils, then altering them through adding a metal base saponifies the fatty acids into soaps.
Typically, the range of properties produced by saponification of a natural oil is rather limited. Thus, there is a need to create metallic soap compositions having a diverse range of properties and applications, and in particular, adhesive properties and anti-corrosion properties on certain surfaces or materials, and as asphalt modifiers to reduce viscosity in an asphalt mixture.